This invention relates to a series of ketolide antibacterials in the macrolide family, intermediates used in their manufacture and pharmaceutical compositions containing them. The compounds are erythromycin analogues useful in the treatment of bacterial and protozoal infections and in the treatment of other conditions involving gastric motility.
Polyketides are a family of natural products that include many compounds possessing antibiotic and other pharmacologic properties. Erythromycins are a class of macrolide antibiotics originally discovered in 1952 in the metabolic products of a strain of Streptomyces erythreus. The antibiotic occurs in various glycosylated forms, designated A, B, C and D. Since their discovery, many have worked to prepare derivatives of the molecule to improve or modify its properties. The focus of much of this work involved chemical modification of the naturally produced erythromycin molecule. This work has produced a number of derivatives including the semi-synthetic antibiotic, clarithromycin, which is 6-O-methylerythromycin. 12,11 oxycarbonyl substituted imino chemical derivatives of erythromycin are described in U.S. Pat. No. 5,635,485. However, because of the complexity of the macrolide molecule, medicinal chemistry efforts to produce derivatives have been limited by the kinds of modifications that can be made to the naturally occurring products.
Recently, work surrounding the search for modified polyketide antibiotics expanded with the discovery and isolation of the modular polyketide synthases (PKS""s); multifunctional enzymes related to fatty acid synthases, which catalyze the biosynthesis of polyketides through repeated reactions between acylthioesters to produce the polyketide chain. The entire biosynthetic gene cluster from S. erythraea has been mapped and sequenced by Donadio et al. in Industrial Microorganisms: Basic and Applied Molecular Genetics (1993) R. H. Baltz, G. D. Hegeman, and P. L. Skatrud (eds.) (Amer. Soc. Microbiol.) and the entire PKS is a modular assembly of three multifunctional proteins encoded by three separate genes. U.S. Pat. No. 5,672,491 discloses the use of cells transformed with recombinant vectors encoding a variety of PKS gene clusters, which can be used to produce a variety of active polyketides. The vectors can include native or hybrid combinations of PKS subunits, or mutants thereof, to produce a variety of polyketide compounds. Cell-free systems which effect the production of polyketides employing modular polyketide synthases are reported in WO 97/02358.
Using these techniques, production of erythromycin analogues in which C-13 bears a substitution other than the natural ethyl group have been reported, for example in WO 98/01571, WO 99/35157, WO 99/03986, and WO 97/02358. WO 98/0156 describes a hybrid modular PKS gene for varying the nature of the starter and extender units to synthesize novel polyketides, including erythromycin analogues. U.S. Pat. Nos. 5,824,513 and 6,004,787 further describe methods to produce polyketide structures by introducing specific genetic alterations to genes encoding PKS in the EryA sequence of S. erythraea. 
The present invention is concerned with novel chemical derivatives of unnatural erythromycin analogues prepared by manipulation of the modular PKS gene clusters.

This invention is concerned with new compounds of the formula I:
wherein:
X is H, F, Cl, Br, or I;
R2is selected from H, xe2x80x94COCH3 and xe2x80x94COPhenyl;
R6 is selected from H and xe2x80x94Oxe2x80x94Ra where Ra is substituted or unsubstituted alkyl (C1-C10), substituted or unsubstituted alkenyl (C2-C10), or substituted or unsubstituted alkynyl(C2-C10);
R13 is selected from H, (C1-C8) alkyl, 1-alkenyl (C2-C8), 1-alkynyl (C2-C8), substituted (C1-C8)alkyl, and xe2x80x94CH2xe2x80x94Rxe2x80x3 where Rxe2x80x3 is selected from H, (C1-C8) alkyl, substituted (C1-C8)alkyl, cycloalkyl, alkenyl (C2-C8), alkynyl (C2-C8), aryl, substituted-aryl, (C1-C8) alkylaryl, heterocyclo, and substituted heterocyclo; provided that R13 can not be ethyl;
R is selected from H, aryl, substituted-aryl, heterocyclo, substituted-heterocyclo, cycloalkyl, C1-8-alkyl and C1-C8-alkenyl optionally substituted with one or more substituents selected from the group of aryl, substituted-aryl, heterocyclo, substituted-heterocyclo, hydroxy, C1-C6-alkoxy;
and the pharmaceutically acceptable salts, esters and pro-drug forms thereof.
Listed below are definitions of various terms used to describe this invention. These definitions apply to the terms as they are used throughout this specification, unless otherwise limited in specific instances, either individually or as part of a larger group.
The term xe2x80x9calkylxe2x80x9d refers to straight or branched chain unsubstituted hydrocarbon groups of the specified number of carbon atoms.
The term xe2x80x9csubstituted alkylxe2x80x9d refers to an alkyl group substituted by, for example, one to four substituents, such as, halo, trifluoromethyl, trifluoromethoxy, hydroxy, alkoxy, cycloalkyloxy, heterocylooxy, oxo, alkanoyl, aryloxy, alkanoyloxy, amino, alkylamino, arylamino, aralkylamino, cycloalkylamino, heterocycloamino, disubstituted amines in which the 2 amino substituents are selected from alkyl, aryl or aralkyl, alkanoylamine, aroylamino, aralkanoylamino, substituted alkanoylamino, substituted arylamino, substituted aralkanoylamino, thiol, alkylthio, arylthio, aralkylthio, cycloalkylthio, heterocyclothio, alkylthiono, arylthiono, aralkylthiono, alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, sulfonamido (e.g. SO2NH2), substituted sulfonamido, nitro, cyano, carboxy, carbamyl (e.g. CONH2) substituted carbamyl (e.g.CONH alkyl, CONH aryl, CONH aralkyl or cases where there are two substituents on the nitrogen selected from alkyl, aryl or aralkyl), alkoxycarbonyl, aryl, substituted aryl, guanidino and heterocycles, such as indolyl, imidazolyl, furyl, thienyl, thiazolyl, pyrrolidyl, pyridyl, pyrimidyl and the like. Where noted above where the substituent is further substituted it will be with halogen, alkyl, alkoxy, aryl or aralkyl.
The term xe2x80x9chalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d refers to fluorine, chlorine, bromine and iodine.
The term xe2x80x9carylxe2x80x9d refers to monocyclic or bicyclic aromatic hydrocarbon groups having 6 to 12 carbon atoms in the ring portion, such as phenyl, napthyl, and biphenyl groups, each of which may be substituted.
The term xe2x80x9calkylarylxe2x80x9d or xe2x80x9caralkylxe2x80x9d refers to an aryl group bonded directly through an alkyl group, such as benzyl.
The term xe2x80x9csubstituted arylxe2x80x9d refers to an aryl group substituted by, for example, one to four substituents such as alkyl; substituted alkyl, halo, trifluoromethoxy, trifluoromethyl, hydroxy, alkoxy, cycloalkyloxy, heterocyclooxy, alkanoyl, alkanoyloxy, amino, alkylamino, aralkylamino, cycloalkylamino, heterocycloamino, dialkylamino, alkanoylamino, thiol, alkylthio, cycloalkylthio, heterocyclothio, ureido, nitro, cyano, carboxy, carboxyalkyl, carbamyl, alkoxycarbonyl, alkylthiono, arylthiono, alkysulfonyl, sulfonamido, aryloxy and the like. The substituent may be further substituted by halo, hydroxy, alkyl, alkoxy, aryl, substituted aryl, substituted alkyl or aralkyl.
The term xe2x80x9ccycloalkylxe2x80x9d refers to optionally substituted, saturated cyclic hydrocarbon ring systems, preferably containing 1 to 3 rings and 3 to 7 carbons per ring which may be further fused with an unsaturated C3-C7 carbocyclic ring. Exemplary groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, and adamantyl. Exemplary substituents include one or more alkyl groups as described above, or one or more groups described above as alkyl substitutents.
The terms xe2x80x9cheterocyclexe2x80x9d, xe2x80x9cheterocyclicxe2x80x9d and xe2x80x9cheterocycloxe2x80x9d refer to an optionally substituted, fully saturated or unsaturated , aromatic or nonaromatic cyclic group, for example, which is a 4 to 7 membered monocyclic, 7 to 11 membered bicyclic, or 10 to 15 membered tricyclic ring system, which has at least one heteroatom in at least one carbon atom-containing ring. Each ring of the heterocyclic group containing a heteroatom may have 1, 2 or 3 heteroatoms selected from nitrogen atoms, oxygen atoms and sulfur atoms, where the nitrogen and sulfur heteroatoms may also optionally be oxidized and the nitrogen heteroatoms may also optionally be quaternized. The heterocyclic group may be attached at any heteroatom or carbon atom.
Exemplary monocyclic heterocyclic groups include pyrrolidinyl, pyrrolyl, indolyl, pyrazolyl, oxetanyl, pyrazolinyl, imidazolyl, imidazolinyl, imidazolidinyl, oxazolyl, oxazolidinyl, isoxazolinyl, isoxazolyl, thizaolyl, thiadiazolyl, thiazolidinyl, isothiazolyl, isothiazolidinyl, furyl, tetrahydrofuryl, thienyl, oxadiazolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxazepinyl, azepinyl, 4-piperidonyl, pyridinyl, N-oxo-pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, tetrahydropyranyl, tetrahydrothiopyranyl, tetrahydrothiopyranyl sulfone, morpholinyl, thiomorpholinyl, thiomorpholinyl sulfoxide, thiomorpholinyl sulfone, 1,3-dioxolane and tetrahydro-1, 1-dioxothienyl, dioxanyl, isothiazolidinyl, thietanyl, thiiranyl, to triazinyl, and triazolyl, and the like. Preferred heterocyclo groups include pyridinyl, pyrazinyl, pyrimidinyl, pyrroyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isoxazolyl, thiadiazolyl, oxadiazolyl, thienyl, furanyl, quinolinyl, isoquinolinyl, and the like.
Exemplary bicyclic heterocyclic groups include benzothiazolyl, benzoxazolyl, benzothienyl, quinuclidinyl, quinolinyl, quinolinyl-N-oxide, tetrahydroisoquinolinyl, isoquinolinyl, benzimidazolyl, benzopyranyl, indolizinyl, benzofuryl, chromonyl, coumarinyl, cinnolinyl, quinoxalinyl, indazolyl, pyrrolopyridinyl, furopyridinyl (such as furo[2,3-c]pyridinyl, furo[3,2-b]pyridinyl), or furo[2,3-b]pyridinyl), imidazopyridinyl (such as imidazo[4,5-b]pyridinyl or imidazo[4,5-c]pyridinyl), dihydroisoindolyl, dihydroquinazolinyl (such as 3,4-dihydro-4-oxo-quinazolinyl), benzisothiazolyl, benzisoxazolyl, benzodiazinyl, benzofurazanyl, benzothiopyranyl, benzotriazolyl, benzpyrazolyl, dihydrobenzofuryl, dihydrobenzothienyl, dihydrobenzothiopyranyl, dihydrobenzothiopyranyl sulfone, dihydrobenzopyranyl, indolinyl, isochromanyl, isoindolinyl, naphthyridinyl, phthalazinyl, piperonyl, purinyl, pyridopyridyl, quinazolinyl, tetrahydroquinolinyl, thienofuryl, thienopyridyl, thienothienyl, and the like.
xe2x80x9cSubstituted heterocycloxe2x80x9d refers to heterocycle substituted by one to four substituents. Exemplary substituents include one or more alkyl groups as described above or one or more groups described above as alkyl substituents. Substituted-heterocyclo may be substituted with a mono-oxo to give for example a 4-oxo-1H-quinoline. Substituted-heterocyclo may also be substituted with a substituted-aryl or a second substituted-heterocyclo to give for example a 4-phenylimidazol-1-yl or a 4-(pyridin-3-yl)-imidazol-1-yl.
The following substituted heterocyclo groups are particularly preferred 
The compounds of the invention are those of formula I as set forth above, as well as any stereoisomeric forms of these compounds as shown. The particular stereoisomers depicted are those resulting from the preferred method of synthesis set forth above and exemplified herein; however, by modifying the expression system for the PKS, or by altering the chirality of the diketide, or by synthetic chemical conversion, other stereoisomers may also be prepared. Additional chiral centers may be present in the substituents, such as Ra and R13. The stereoisomers may be administered as mixtures, or individual stereoisomers may be separated and utilized as is known in the art.
The compounds are expected to possess antibacterial activity against Gram positive, Gram negative, and anaerobic bacteria due to their novel structure, and are expected to be useful as broad spectrum antibacterial agents for the treatment of bacterial infections in humans and animals. These compounds are particularly expected to have antimicrobial activity against S. aureus, S. epidermidis, S. pneumoniae, S. pyogenes, enterococci, Moraxella catarrhalis and H. influenzae. These compounds are particularly expected to be useful in the treatment of community-acquired pneumonia, upper and lower respiratory tract infections, skin and soft tissue infections, meningitis, hospital-acquired lung infections, and bone and joint infections.
Also included in the present invention are compounds useful as intermediates or producing the compounds of the present invention. Such intermediate compounds include those of the formula: 
Wherein X, R6 and R13 are as described above, and R2 is hydrogen or a hydroxyl protecting group, such as acetyl, benzoyl, or trimethylsilyl. Other intermediates included within the scope of this invention are those of the formula: 
Wherein X, R6 and R13 are as described above, and R2 is hydrogen or a hydroxyl protecting group, such as acetyl, benzoyl, or trimethylsilyl.
Preferred compounds are those of Formula I wherein:
X is H or F;
R2 is as described above,
R6 is selected from H and (C1-C8) alkoxy;
R13 is selected from H, (C1-C4) alkyl, 1-alkenyl (C2-C8) (particularly vinyl), 1-alkynyl (C2-C8), haloalkyl, and xe2x80x94CH2xe2x80x94Rxe2x80x3 where Rxe2x80x3 is selected from H, (C1-C8) alkyl, haloalkyl, 1-alkenyl (C2-C8), 1-alkynyl (C2-C8), phenyl, and (C1-C8) alkylphenyl (such as benzyl and phenethyl);
provided that R13 can not be ethyl;
R is selected from H, aryl, substituted-aryl, heterocyclo, substituted-heterocyclo, cycloalkyl, C1-C8-alkyl and C1-C8-alkenyl optionally substituted with one or more substituents selected from the group of aryl, substituted-aryl, heterocyclo, substituted-heterocyclo, hydroxy, C1-C6-alkoxy;
and the pharmaceutically acceptable salts, esters and pro-drug forms thereof.
Particularly preferred groups for R include H, phenyl, C1-C8-alkyl or C1-C8-alkenyl optionally substituted with one or more substituents selected from the group of phenyl, hydroxy, and the following substituted heterocyclo groups. 
Another group of preferred compounds are those of the formula I wherein:
X is H or F;
R2 is as described above,
R6 is Oxe2x80x94Ra where Ra is substituted or unsubstituted alkyl (C1-C10), substituted or unsubstituted alkenyl (C2-C10), or substituted or unsubstituted alkynyl(C2-C10);
R13 is selected from H, (C1-C8) alkyl, 1-alkenyl (C2-C8)(particularly vinyl), 1-alkynyl (C2-C8), haloalkyl, and xe2x80x94CH2xe2x80x94Rxe2x80x3 where Rxe2x80x3 is selected from H, (C1-C8) alkyl, haloalkyl, 1-alkenyl (C2-C8), 1-alkynyl (C2-C8), phenyl, and (C1-C8) alkylphenyl (such as benzyl and phenethyl);
provided that R13 can not be ethyl;
R is H;
and the pharmaceutically acceptable salts, esters and pro-drug forms thereof.
Particularly preferred groups for include optionally substituted 3-(quinolin-3-yl)prop-2-enyl, optionally substituted 3-(quinolin-3-yl)prop-2-ynyl, optionally substituted 3-(quinolin-6-yl)prop-2-enyl, optionally substituted 3-(quinolin-6-yl)prop-2-ynyl, optionally substituted 3-(quinolin-7-yl)prop-2-enyl, optionally substituted 3-phenylprop-2-enyl, optionally substituted 3-(naphth-1-yl)prop-2-enyl, optionally substituted 3-(naphth-1-yl)prop-2-ynyl, optionally substituted 3-(naphth-2-yl)prop-2-enyl, optionally substituted 3-(naphth-2-yl)prop-2-ynyl, optionally substituted 5-phenylpent-4-en-2-ynyl, optionally substituted 3-(fur-2-yl)prop-2-ynyl, optionally substituted 3-(thien-2-yl)prop-2-enyl, optionally substituted 3-(carbazol-3-yl)prop-2-enyl, and optionally substituted 3-(quinoxalin-6-yl)prop-2-enyl.
The preferred compounds of this invention may be prepared according to the following reaction schemes: 
The preferred compounds of the invention wherein R6 is hydrogen may be prepared according to the following reaction scheme: 
The starting macrolide intermediates, 4 and 5, may be prepared by methods described in U.S. Pat. No. 5,672,491, hereby incorporated by reference into the present application. In one embodiment, modified erythromycin intermediates, 4 and 5, may be prepared by a method in which an appropriate thioester diketide substrate is provided to 6-deoxyerythronolide B synthase (DEBS) that is unable to act on its natural substrate (propionyl CoA) due to a mutation in the ketosynthase domain of module 1 of DEBS. This recombinant DEBS can be expressed in the organism that natively produces erythromycin, Saccharopolyspora erythraea, or the entire gene cluster can be inserted by plasmid in a suitable host such as S. coelicolor (Jacobsen et al, Science 277:367-369 (1997)) or S. lividans, preferably an S. coelicolor or S. lividans which has been modified to delete its endogeneous actinorhodin polyketide synthesis mechanism. A suitable host would be S. coelicolor CH999/pJRJ2, which expresses a mutant 6-DEB synthase having an inactivated module 1 ketosynthase.
A cell free system as described in WO 97/02358 may also be employed by producing the relevant PKS proteins recombinantly and effecting their secretion or lysing the cells containing them. A typical cell-free system would include the appropriate PKS, NADPH and an appropriate buffer and substrates required for the catalytic synthesis of polyketides.
Further, the appropriate thioester diketide substrate can be provided to PKS enzymes other than the 6-DEB synthase of Saccharopolyspora erythraea. Other PKS enzymes include the 6-DEB synthase of Micromonospora megalomicea and its KS1xc2x0 derivative described in U.S. Ser. No. 60/158305, the oleandolide PKS and its KS1xc2x0 derivative described in PCT application No. US 99/24478, and the narbonolide PKS and its KS1xc2x0 derivative described in PCT publication No. WO 99/61599, all incorporated by reference herein.
For those macrolide intermediates, 4 and 5, where R13 is methyl, no diketide feeding is required because the desired aglycone may be produced by the recombinant host cell Streptomyces coelicolor CH999/pCK7, as further described herein.
The resulting aglycones thus prepared are then added to the fermentation broth of Saccharopolyspora erythraea strains which chemically glycosylate at the 3 and 5 positions, hydroxylate at C-12, and optionally hydroxylate at the 6 position, depending on the strain employed.
The modified erythromycins of the invention, in addition to modification at C-13, contain an xe2x80x94OH group at position 6 unless xe2x80x94OH is replaced by H or ORa as described above. To construct, ultimately, the compounds of formula I where position 6 is ORa, the compound of formula (4) is provided with protecting groups on the hydroxyl groups of the two glycose residues (Scheme 1). Such protection is effected using suitable protecting reagents such as acetic anhydride, benzoic anhydride, benzyl chloroformate, hexamethyldisilazane, or a trialkylsilyl chloride in an aprotic solvent. Aprotic solvents include, for example, dichloromethane, chloroform, tetrahydrofaran, N-methyl pyrrolidone, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF) and the like. Mixtures may also be used. Protection of both sugar hydroxyls in formula (4) may be done simultaneously or sequentially.
In addition to protecting the 2xe2x80x2 and 4xe2x80x3 hydroxyl groups of the two glycose residues, the keto group at position 9 of the macrolide ring must also be protected. Typically, this is effected by converting the keto group to a derivatized oxime. Particularly preferred embodiments for R in the formula xe2x95x90NOR include unsubstituted or substituted alkyl (1-12C), substituted or unsubstituted aryl (6-10C), alkyl (1-12C), substituted or unsubstituted heteroaryl (6-10C), alkyl (1-12C), and heteroalkyl (such as substituents of the formula CRxe2x80x22OR wherein each Rxe2x80x2, in addition to being independently embodied as R as set forth above, may, together with the other, form a cycloalkyl ring (3-12C)). A preferred derivatized oxime is of the formula xe2x95x90NOR wherein R is isopropoxycyclohexyl.
With the 9-keto group and the 2xe2x80x2 and 4xe2x80x3 hydroxyls protected, it is then possible to alkylate the 6-hydroxy group in the compound of formula (8) by reaction with an alkylating agent in the presence of base. Alkylating agents include alkyl halides and sulfonates. For example, the alkylating agents may include methyl tosylate, 2-fluoroethyl bromide, cinnamyl bromide, crotonyl bromide, allyl bromide, propargyl bromide, and the like. The alkylation is conducted in the presence of base, such as potassium hydroxide, sodium hydride, potassium isopropoxide, potassium t-butoxide, and an aprotic solvent.
The choice of alkylating agent will depend on the nature of the substituents Ra to be included. As set forth above, Ra can be substituted or unsubstituted alkyl (1-10C), substituted or unsubstituted alkenyl (2-10C), or substituted or unsubstituted alkynyl (2-10C). Particularly preferred are unsubstituted alkyl, alkenyl, or alkynyl, or substituted forms of these wherein the substituents include one or more halogen, hydroxy, alkoxy (1-6C), oxo, SO2R (1-6C), N3, CN, and NR2 wherein R is H, substituted or unsubstituted alkyl (including cycloalkyl) (1-12C), substituted or unsubstituted alkenyl (including cycloalkenyl) (2-12C), alkynyl (including cycloalkynyl) (2-12C), substituted or unsubstituted aryl (6-10C), including the hetero forms of the above.
Especially preferred are methyl, allyl and ethyl.
Once the alkylation of the 6-hydroxyl is completed, the sugar residues and the macrolide ring may be deprotected. Deprotection of the glycoside moieties is conducted as described by Green, T. W., et al., in Protective Groups in Organic Synthesis, infra. Similar conditions result in converting the derivatized oxime to xe2x95x90NOH. If formation of the underivatized oxime is not concurrent with deprotection, the conversion to the oxime is conducted separately.
The oxime can then be removed and converted to a keto group by standard methods known in the art. Deoximating agents include inorganic sulfur oxide compounds such as sodium hydrogen sulfite, sodium pyrosulfate, sodium thiosulfate, and the like. In this case, protic solvents are used, such as water, methanol, ethanol, isopropanol, trimethyl silanol and mixtures of these. In general, the deoximation reaction is conducted in the presence of an organic acid.
At this point in the process, or later, the group introduced at the 6-hydroxyl can further be manipulated. Conveniently, the initial substitution may provide a 6-O-allyl, i.e., Oxe2x80x94CH2CHxe2x95x90CH2, which can further be derivatized by reduction to give the 6-O propyl compound, or be treated with osmium tetroxide to provide the 2,3-dihydroxypropyl compound, which can further be esterified at each oxygen atom. The O-allyl derivative can also be oxidized with m-chloroperoxybenzoic acid in an aprotic solvent to provide the epoxy compound which can be opened with amines or N-containing heteroaryl compounds to provide compounds with N-containing side-chains, or can be oxidized under Wacker conditions to provide the substituent Oxe2x80x94CH2xe2x80x94C(O)xe2x80x94CH3, or can be ozonized to provide the aldehyde. The aldehyde can then be converted to the oxime or reacted with a suitable amine and reduced in the presence of a borohydride reducing agent to provide an amine. The oxime can also be converted to a nitrile by reaction with a dehydration agent in an aprotic solvent. The O-allyl derivative can also be reacted with an aryl halide under Heck conditions (Pd(II) or Pd(O), phosphine and amine or inorganic base) to provide a 3-aryl prop-2-enyl derivative (Scheme 3). This derivative can then be reduced with hydrogen and palladium on carbon to provide a 3-arylpropyl derivative. If the initial substituent Ra is a 2-propyne, similar reactions can be employed to provide alterations in the side-chain, including arylation.
In order to convert the compound of formula (11) into the compound of formula (12), by first removing the cladinose moiety, the compound of formula (11) is treated with mild aqueous acid or with a deglycosylating enzyme (Scheme 1). Suitable acids include hydrochloric, sulfuric, chloroacetic, trifluoroacetic and the like, in the presence of alcohol. Reaction times are typically 0.5-24 hours at a temperature of xe2x88x9210-35xc2x0 C. Following protection of the 2xe2x80x2 hydroxyl of the remaining sugar as set forth above, the resulting hydroxyl group at the 3-position of the macrolide ring is then oxidized to the ketone using a modified Swern oxidation procedure. In this procedure, an oxidizing agent such as N-chlorosuccinimide-dimethyl sulfide or a carbodiimide-dimethylsuloxide is used. Typically, a compound of formula (13) is added to a pre-formed N-chlorosuccinimide and dimethyl sulfide complex in a chlorinated solvent such as methylene chloride at xe2x88x9210-25xc2x0 C. After being stirred for 0.5-4 hours, a tertiary amine such as triethylamine is added to produce the corresponding ketone.
Intermediate (16) can then be prepared from intermediate (14) in a two-step procedure as illustrated in Scheme 1. First the 11-hydroxyl group is preferentially converted to a leaving group, such as methanesulfonate, by reaction with an alkyl or arylsulfonyl chloride, such as methanesulfonyl chloride, in the presence of an organic base, like pyridine. In the next step, the leaving group is eliminated to afford the 10-11 double bond by treatment with diazabicycloundecane in a suitable solvent like acetone.
In order to halogenate the macrolide at position 2 (converting X=H to halogen), the compound of formula (16), is treated with a base and an electrophilic halogenating reagent such as pyridinium perbromide or N-fluorobenzene sulfonic acid.
In accordance with Scheme 2, intermediate (18) is reacted with sodium hydride and 1,1xe2x80x2-carbonyldiimidazole to yield the imidazole intermediate (19). Intermediate (19) is then reacted with the appropriate substituted amine in dimethylformamide at about 25xc2x0 to 130xc2x0 and then the hydroxy protecting group is removed by treatment with methanol to yield the final compound I.
In a similar fashion (Scheme 3), intermediate (20) can be converted to the unsubstituted 11,12-cyclic carbamate intermediate (21) by reaction of the analogous imidazole intermediate with aqueous ammonia. As mentioned earlier, the 6-position substituent can be manipulated late in the synthetic sequence, and this is illustrated in Scheme 3, where the 6-O-allyl derivative is reacted with an aryl halide under Heck conditions (Pd(II) or Pd(O), phosphine and amine or inorganic base) to provide a 3-aryl prop-2-enyl derivative. Subsequent deprotection of the 2xe2x80x2 hydroxyl group affords the final compound I.
It will also be noted that compounds of the invention wherein R6 is hydrogen can be readily obtained from a mixture of 6-deoxy-13-substituted-erythromycins A, B, C, and D derived from fermentation. A similar series of reactions as described above can be used to effect this conversion (Scheme 4).
This invention further provides a method of treating bacterial infections, or enhancing the activity of other antibacterial agents, in warm-blooded animals, which comprises administering to the animals a compound of the invention alone or in admixture with a diluent or in the form of a medicament according to the invention.
When the compounds are employed for the above utility, they may be combined with one or more pharmaceutically acceptable carriers, e.g., solvents, diluents, and the like, and may be administered orally in such forms as tablets, capsules, dispersible powders, granules, or suspensions containing for example, from about 0.5% to 5% of suspending agent, syrups containing, for example, from about 10% to 50% of sugar, and elixirs containing, for example, from about 20% to 50% ethanol, and the like, or parenterally in the form of sterile injectable solutions or suspensions containing from about 0.5% to 5% suspending agent in an isotonic medium. These pharmaceutical preparations may contain, for example, from about 0.5% up to about 90% of the active ingredient in combination with the carrier, more usually between 5% and 60% by weight.
Compositions for topical application may take the form of liquids, creams or gels, containing a therapeutically effective concentration of a compound of the invention admixed with a dermatologically acceptable carrier.
In preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed. Solid carriers include starch, lactose, dicalcium phosphate, microcrystalline cellulose, sucrose and kaolin, while liquid carriers include sterile water, polyethylene glycols, non-ionic surfactants and edible oils such as corn, peanut and sesame oils, as are appropriate to the nature of the active ingredient and the particular form of administration desired. Adjuvants customarily employed in the preparation of pharmaceutical compositions may be advantageously included, such as flavoring agents, coloring agents, preserving agents, and antioxidants, for example, vitamin E, ascorbic acid, BHT and BHA.
The preferred pharmaceutical compositions from the standpoint of ease of preparation and administration are solid compositions, particularly tablets and hard-filled or liquid-filled capsules. Oral administration of the compounds is preferred.
These active compounds may also be administered parenterally or intraperitoneally. Solutions or suspensions of these active compounds as a free base or pharmacologically acceptable salt can be prepared in water suitably mixed with a surfactant such as hydroxypropyl-cellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols and mixtures thereof in oils. Under ordinary conditions of storage and use, these preparations may contain a preservative to prevent the growth of microorganisms.
The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and must be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g., glycerol, propylene glycol and liquid polyethylene glycol), suitable mixtures thereof, and vegetable oils.
The effective dosage of active ingredient employed may vary depending on the particular compound employed, the mode of administration and the severity of the condition being treated. However, in general, satisfactory results are obtained when the compounds of the invention are administered at a daily dosage of from about 0.1 mg/kg to about 400 mg/kg of animal body weight, preferably given once a day, or in divided doses two to four times a day, or in sustained release form. For most large mammals the total daily dosage is from about 0.07 g to 7.0 g, preferably from about 100 mg to 1000 mg Dosage forms suitable for internal use comprise from about 100 mg to 500 mg of the active compound in intimate admixture with a solid or liquid pharmaceutically acceptable carrier. This dosage regimen may be adjusted to provide the optimal therapeutic response. For example, several divided doses may be administered daily or the dose may be proportionally reduced as indicated by the exigencies of the therapeutic situation.
The production of the above-mentioned pharmaceutical compositions and medicaments is carried out by any method known in the art, for example, by mixing the active ingredients(s) with the diluent(s) to form a pharmaceutical composition (e.g. a granulate) and then forming the composition into the medicament (e.g. tablets).